In recent years, there have been increasingly strict demands for silver halide photographic light-sensitive materials as to photographic performance stability, as well as high sensitivity and high image quality. For example, there is a need for improved resistance against pressure to which the silver halide photographic light-sensitive material being handled in picture taking, processing or other photographic operation, is exposed in various manners, whether accidentally or inevitably, from the viewpoint of photographic performance stabilization. Accordingly, various technical improvements have been proposed, mainly for silver halide photographic emulsions.
Meantime, quick processing at high temperatures has rapidly gained popularity for the processing of silver halide photographic light-sensitive materials; processing time has shortened in automatic processing of various silver halide photographic light-sensitive materials using automatic processing machines. For the purpose of rapid processing, it is necessary to offer sufficient sensitivity and gradation in short time.
Examples of traditional means of improving the anti-pressure properties of silver halide photographic light-sensitive materials include those described in U.S. Pat. No. 2,628,167 and Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 116025/1975 and 107129/1976, in which an iridium salt or thallium salt is added at the time of silver halide grain formation. However, these methods have a drawback of sensitivity reduction.
Also, Japanese Patent O.P.I. Publication Nos. 220238/1988 and 201649/1989 disclose improvements of the granularity, anti-pressure properties and exposure luminance dependence of silver halide photographic light-sensitive materials, while maintaining high sensitivity, by introducing dislocation to silver halide grains.
However, these prior art methods are subject to limitation as to the simultaneous improvement of anti-pressure properties and developability, so that they are unsatisfactory to meet the recent requirements of stable photographic performance and rapid processibility for current silver halide photographic light-sensitive materials. There is therefore a need for a further improved method.